1. Field of Endeavor
This invention relates to establishing and operating virtual private data networks.
2. Brief Description of the Related Art
Virtual private networks (VPNs) leverage the flexibility and cost advantages of the Internet by passing information over the Internet, or other shared Internet Protocol (IP) network, in a secure manner. VPNs enable enterprises to securely bridge geographically separated computers or local networks over the Internet as an alternative to using expensive, leased-line networks and other remote-access solutions. Internet Service Providers (ISPs), recognizing the benefits of VPNs, are beginning to offer multi-tiered VPN services to their customers.
Businesses, recognizing the benefits of VPNs, employ VPNs to support a wide variety of connectivity needs including remote dial-up access for telecommuters and mobile users, private line augmentation and replacement of existing leased-line and frame relay networks, extranet networking for secure and controlled wide area access to corporate information resources by their business partners, and segmented intranet networking for secure partitioning of internal traffic across both the wide area and the local area.
An important impetus for the adoption of VPN technology by businesses is the significant cost saving associated with the replacement of expensive remote access servers and associated long distance dial-up charges, the substitution of inexpensive and ubiquitous Internet access for expensive leased lines and frame relay access, and the introduction of a flexible, fast, secure, and inexpensive mechanism for exchanging data with suppliers and customers.
At the present time, a number of standards and proprietary schemes exist for encrypting and authenticating data packets that traverse public or private data networks. In December 1995, the Internet Engineering Task Force (IETF) published five Requests for Comments (RFCs) that define formats and methods for encrypting and authenticating Internet Protocol (IP) packets. More recently, the IETF has published a series of Internet Drafts that update the formats and methods for encrypting and authenticating IP packets. The IETF initiative is called Internet Protocol Security (IPSec).
The IETF is currently in the process of defining a data link layer security protocol that is known by the name Layer 2 Tunneling Protocol (L2TP). L2TP encapsulates data link layer PPP frames and transmits them across public data networks by prepending an IP header to the encapsulated PPP frames.
Microsoft Corporation has implemented a proprietary data link layer security protocol called Point to Point Tunneling Protocol (PPTP) that encrypts data layer PPP frames and transmits them across public data networks by prepending an IP header to the encrypted PPP frames.
The IETF has also published a series of Internet Drafts intended to address the standardization of a key management protocol by which IPSec devices negotiate their security associations and keying material. The original name for this key management scheme was called ISAKMP/OAKLEY; the more current name is the Internet Key Exchange (IKE).